<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		.box{
			width: 200px;
			height: 200px;
			background: rgba(0,0,0,0.5) url() 0 0 no-repeat;
			/*opacity: 1;*/
		}
	</style>
	<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
	<script>
		$(function(){

			$('#box').css('color','red');

			$('span').css('color','blue');

			$('#box .span1').css('color','green');

			$('#baidu').attr('id','sdfdsf');
			$('#baidu').addClass('cur');

			$('input').val();

			$('span').click(function(event) {
				alert(777)
			});

			$('span').mouseover(function(event) {
				/* Act on the event */
			});

			$('span').dblclick(function(event) {
				/* Act on the event */
			});

			$('span').focus(function(event) {
				/* Act on the event */
			});

			$('span').hover(function() {
				/* Stuff to do when the mouse enters the element */
			}, function() {
				/* Stuff to do when the mouse leaves the element */
			});

			$('span').show();
		})
	</script>
</head>
<body>
	<div id="box" class="box">
		学并思
		<span>span1</span>
		<span class="span1">span2</span>
	</div>
	<span class="span1">span2</span>
	<a href="http//www.baidu.com" id="baidu" name="xuwibngis" age='18'></a>
	<input type="text">
</body>
</html>